Phosphonous acid esters

ABSTRACT

Compounds, useful as stablizers for organic materials, of the formula   WHEREIN X is -CH2-, -O- or -S-, Y1, Y2, Y3 and Y4 are -O- or -S-, R1, R2, R3 and R4 are hydrocarbon radicals, rings A and B may be substituted by alkyl groups, AND INORGANIC SALTS OF COMPOUNDS IN WHICH ANY OF R1-R4 are hydrogen.

i United States Patent 1 [111 3,875,264 Hofer et al. Apr. 1, 1975PHOSPHONOUS ACID ESTERS [75] Inventors: Kurt Hofer, Munchenstein/BL; iExamuierwLoframe wemberger Guemher Tscheulin Riehen/BS AssistantE.\'ammerRichard L. Raymond both of Switzerland Attorney, Agent, orFirmGerald D. Sharkin; Richard E. Vila; Thomas C. Doyle [73] Assignee:Sandoz Ltd. (also known as Sandoz,

AG), Basie, Switzerland 57 ABSTRACT [22] Filed: Nov. 21, 1972 Compounds,useful as stablizers for organic materials, 21 Appl. No.: 308,594 offmmula [30] Foreign Application Priority Data T R3 Nov. 24, l97lSwitzerland l7l29/7l P p 52 vs. CI 260/932, 260/45.7 PS, 260/45.7 P,R,-Y1 q y R, 260/448 R, 260/502.4 R, 260/502.4 P, Wherffin 260/949,260/951, 260/962, 260/972, 260/973 X 15 2 0- or S, [51] Int. Cl. C07f9/08, C07f 9/16 1 2 3 and 4 are or [58] Field of Search 260/932 1, 2Raiand are hy r r on i l r ng A and B may be substituted by alkylgroups, [56] I References Cited and inorganic salts of compounds inwhich any of UNITED STATES PATENTS RrRi are hydrogen- 3,707,565 12/1972Hofer 260/962 19 Claims, No Drawings 1 PHOSPIIONOUS ACll) E-STERSIMPROVEMENTS IN OR RELATING TO ORGANIC COMPOUNDS The present inventionrelates to phosphonous acid derivatives.

More particularly, this invention provides compounds of formula I,

Y Y Y and Y which may be the the same or different, each signifies O orS.

R R R and R which may be the the same or different, each signifies ahydrocarbon radical of up to carbon atoms consisting of aromatic and/orsaturated aliphatic units,

and rings A and B may be either further unsubstituted or each furthersubstituted by I or 2 alkyl groups of l to 6 carbon atoms, and inorganicsalts of compounds in which any of R to to R is hydrogen.

X preferably signifies O and n preferably signifies 1. Y Y Y and Y, arepreferably the same, and R R R and R, are preferably also the same. Inthe preferred compounds, the

substituent or each substituent is in the para position of the nucleus.

Suitable hydrocarbon radicals for R R R and R include the following:alkyl radicals, preferably other than tertiary alkyl radicals, of up to20, preferably up to 12, in particular I to 6 carbon atoms, for examplen-alkyl radicals such as methyl, ethyl, propyl, butyl, pentyl, hexyl,heptyl, octyl, nonyl, decyl, undecycl and dodecyl, secondary alkylradicals such as isopropyl, 2- butyl, 3-methyl-2-butyl, 2-pentyl,2,2-dimethyl-3-butyl, 2-hexyl, 3-hexyl, 2-methyl-3-phenyl, 3 methyl-2-pentyl, 4-methyl-2-pentyl, 2,2-dimethyl-3-pentyl, 2,4-dimethyl-3-pentyl,2-heptyl, 3 heptyl, 4-heptyl, 2-methyl-3-hexyl, 4-methyl-3-hexyl,5-methyl-3-hexyl, 3-ethyl-4-hexyl, 2,2-dimethyl-3-hexyl, 2,4-dimethyl-3-hexyl, 2,5-dimethyl-3-hexyl, 3,4-dimethyl-2-hexyl, 2-methyl-3-heptyl,3-methyl-2-heptyl, 3-methyl-4- heptyl, 4-methyl-3-heptyl,5-methyl-3-heptyl, 6 methyl-2-heptyl, 2-octyl, 3-octyl, 4-octyl,2,2,4-trimethyl-3- pentyl, S-ethyl-Z-heptyl, .2,2 -dimethyl-3-heptyl,2,6-dimethyl-4-heptyl, 2-methyl-3-octyl, 3-methyl-4- octyl,6-ethyl-3-octyl, 2-decyl, 5-decyl, 2,2-dimethyl-3- 2 octyl,2-methyl-4-nonyl, 3-methyl-4-nonyl, 6-ethyl-3- decyl,7ethyLZ-methyl-4-nonyl, 2dodecyl, 2,6,8- trimethyl-4-nonyl, Z-tridecyl,2-tetradecyl, 2- pentade'cyl, 2-hexadecyl, 2-nonadecyl, alkyl radicalsbound through a primary carbon atom but otherwise branched, for exampleZ-methyl-l-propyl, 2,2-dimethyl-l-propyl, Z-methyl-l-butyl,2-ethyl-1-butyl, 2,2- dimethyl-l-butyl, Z-methyl-l-pentyl, 3-methyl-1-pentyl, 4-methyl-l-pentyl, 2,4-dimethyl-l-pentyl, 2- ethyl-l-hexyl,2,2-dimethyl-1-hexyl, 2,2,4-trimethyl-1- pentyl,4-methyl-2propyl-l-pentyl, 3,7-dimethyl-loctyl, 2,2-dimethyl-l-decyl;cycloalkyl radicals of up to 20, preferably 3 to 12, in particular 5 to8 carbon atoms, optionally substituted by l, 2 or 3 alkyl radicals, forexample of l to 4 carbon atoms, such as cyclopentyl, cyclohexyl,cycloheptyl, 2-, 3- or 4-methylcyclohexyl, cyclooctyl, 2,5-, 2,6-, 3,4-or 3,5-dimethylcyclohexyl, l-cyclohexylpropyl, Z-propylcyclohexyl,3,3,5-trimethylcyclohexyl, Z-butylcyclohexyl, 4-tert- .butylcyclohexyl,3-methyl-6-iso-propylcyclohexyl, cyclododecyl, l-methylcyclopentyl,l-methylcyclohexyl, l-methylcycloheptyl, l-propylcyclopentyl,l-butylcyclopentyl, l-butylcyclohexyl and l-pentylcyclopentyl;cycloalkylalkyl radicals, in particular C cycloalkyl C alkyl radicals,for example cyclohexyl-methyl, 2- cyclohexyl-ethyl, cycloheptylmethyl,3- cyclohexylpropyl, cyclooctylmethyl, cycloundecylmethyl andcyclododecylmethyl; aryl radicals, for example phenyl or diphenyl,optionally substituted by l, 2 or 3 alkyl radicals, e.g. of 1 to 12,preferably l to 6 carbon atoms, such as those alkyl radicals mentionedabove and also tertiary alkyl radicals, such as tert. butyl,2-methyl-2-butyl, 2,3-dimethyl-2-butyl, Z-methyl- Z-pentyl,3-methyl-3-pentyl, 3-ethyl-3-pentyl, 2,4-dimethyl-2-pentyl,2-methyl'2-hexyl, 3methyl-3- hexyl, 3,4-dimethyl-3-hexyl,3,5-dimethyl-3-hexyl, 2-methyl-2-heptyl, 3-methyl-3-heptyl, 4-methyl-4-heptyl, 2,3,4-trimethyl-3-pentyl, 2,4,4-trimethyl-2- pentyl,3-ethyl-3-heptyl, 2-methyl-2-octyl, 4-methyl-4- octyl,3,6-dimethyl-3-octyl, 3,7-dimethyl-3-octyl, 4,4,-4,6,6-pentamethyl-Z-heptyl, as well as l-alkyl substituted cycloalkylradicals, such as those mentioned above; examples of such substitutedaryl radicals include 2-, 3- and 4-methylphenyl, 2,3-, 2,4-, 2,5-, 3,4-and 3,5-dimethylphenyl, 2-, 3 and 4-ethylphenyl, 2,3,5- and2,4,5-trimethylphenyl, 3-ethyl-5- methylphenyl, 4-sec.butyl-phenyl, 2-and 4- tert.butylphenyl, 5isopropyl-2-methylphenyl, 2-isopropyl-5-methylphenyl, 3-isopropyl-5methylphenyl, 4-tert.pentylphenyl, 2-tert.butyl-4-methylphenyl, 4-tert.butyl-2- methylphenyl,6-tert.butyl-3-methylphenyl, 2,4-ditert.butylphenyl,4-(1',l',3,3-tetramethylbutyl)- phenyl, 2-methyl-4-( l ,l',33-tetramethylbutyl)- phenyl, 4-nonylphenyl (mixture of isomers), and2,4-di-terLoctyl-phenyl; aralkyl radicals, such as phenyl or diphenylalkyl radicals, the alkyl radicals of which suitably contain 1 to 12,particularly 1 to 6 carbon atoms, and the aryl radicals of which mayoptionally be alkyl substituted as above, including benzyl, landZ-phenyl-ethyl, l-phenyl-l-propyl, l-phenyl-Z- propyl,2-phenyl-1-propyl, 3-phenyl-l-propyl, l-(otolyl)-ethyl, 1-(m-tolyl)ethyl, l-(p-tolyl)-ethyl, lphenyl-l-butyl,2-(2,4;6-trimethyl-phenyl)-ethyl, l-phenyl- 1 pentyl,l-(4-tert.butyl-phenyl )-ethyl, 4-methyl-l-phenyl-2-pentyl andbenzohydryl. The preferred hydrocarbon radicals for R R R and R includealkyl radicals, other than tertiary alkyl radicals,

of l to 12, in particular 4 to 12 carbon atoms, such as n-butyl orn-dodecyl, and phenyl and diphenyl radicals, optionally substituted by 1or 2 alkyl radicals of 1 to 4 carbon atoms, preferably tertiary suchalkyl radicals, such as 2,4-di-t-butylphenyl, 2-t-butyl-diphenyl, and2,4'-di-t-butyldiphenyl.

The rings A and B may, as indicated, be substituted by l or 2 alkylgroups of up to 6, preferably up to 4 carbon atoms, for example suchalkyl groups as mentioned above, but are preferably unsubstituted.

The invention also provides a process for the production of compounds offormula I and inorganic salts thereof, characterised by reacting acompound of formula II,

a /Hal Hal X Hal in which X, n and rings A and B are as defined above,

and

the radicals Hal, which may be the same or different, each signify ahalogen atom, with compounds of formula III and IV,

in which R,, R Y, and Y 2 are as defined above, and, if n signifies l,with compounds of formula V and VI.

v VI

in which R R Y and Y, are as defined above, and, where required,converting the resulting product into an inorganic salt. As will beappreciated, two or more of the compounds III, IV, V and VI may be thesame, in which case the molar quantity of the compound is adjustedaccordingly.

The process of the invention may suitably be carried out in conventionalmanner, for example as described by K. Sasse, Houben-Weyl (eds.),Methoden der organischen Chemie, fourth impression (1963), Vol. XII/l.pp.3 l 8/ff. As will also be appreciated, however, the particularconditions employed depend, to an extent, on the particular compoundsIII, IV, V or VI being employed. For example, in some instances, it maybe advisable to apply external cooling to the reaction mixture torestrain the vigorous reaction. Thus, for example, when any of thecompounds III, IV, V and V1 is water, then it is preferable to chargethe reaction mixture with an excess of water and to add the compound IIwith cooling and stirring and at a rate slow enough to ensure that theexothermic reaction does not lead to an unduly high temperature. Wherethe compounds III, IV, V or VI are alcohols or phenols, the reaction maysuitable be carried out at a temperature of from 100 to 150C, in thepresence of an acid binding agent such as pyridine or a trialkylamine.

Where the compound II is reacted with water, products are formedcontaining radicals of formula VIIa and VII b,

VIIa VIIb which are acidic and may be converted into inorganic salts.

Conversion of the acidic compounds into inorganic salts may be effectedin conventional manner. Suitable salts include alkali metal, e.g. sodiumor potassium, al-

kaline earth metal, e.g. calcium or magnesium, zinc, manganese,aluminium, copper, vanadium, cobalt and nickel salts. The salts may beproduced by reaction of the free acid with an inorganic hydroxide orsalt, such as calcium hydroxide, zinc oxide, sodium carbonate, potassiumbicarbonate, aluminium acetate, borium chloride, nickel acetate and zincchloride.

Preferably, however, the reaction of the compounds II with water andproduction of salts is carried out in a single operation. For thispurpose, an excess of water may be provided for hydrolysis of thecompound II, and after addition of the appropriate inorganic reagent,the compound II may be slowly added, with stirring, as indicated above.

The resulting compounds of formula I and inorganic salts thereof may beisolated and purified using conventional techniques.

The compounds of formula II, employed as starting materials are eitherknown or may be produced in conventional manner from availablematerials, for example as described by K. Sasse, Houben-Wehl (eds),Methoden der organischen Chemie, fourth impression 1963), Vol. XII/lorganische Phosphorverbindungen, Part I, pp.302-3 18. Thus, for example,the compound IIa,

is described in Journal of the Chemical Society, 1932, 2880. In general,compounds of formula II may be produced by reacting the appropriatediphenylmethane, oxide or sulphide, with a phosphorus trihalide,preferably phosphorus trichloride. The process may suitably be effectedat an elevated temperature in the gaseous phase, although it is morepreferable to react under milder conditions in the presence of acatalyst, e.g. a F riedel-Krafts catalyst, in particular aluminiumtrichloride. It is preferable to work with phosphorus trichloride at itsboiling temperature. After reaction, any aluminium chloride complex ofthe compound II may be decomposed, for example with phosphorusoxychloride or pyridine.

The resulting compounds of formula Il may be isolated and purified usingconventional techniques.

The compounds of the invention are useful as stabilisers for organicmaterials which are sensitive to light, oxygen and heat. For thispurpose, they may be incorporated in or applied to form a protectivesurface film on the organic material. When thus applied, the newcompounds by their stabilizing action protect sensitive materialsagainst degradation. They have a wide area of use in the processing ofplastics materials, being suitable, for example, as stabilizers forcellulose acetate, cellulose acetobutyrate, polyethylene, polypropylene,polyvinyl chloride, polyvinyl chloride acetate, polyamides, polystyrene,ethyl cellulose, cellulose nitrate, polyvinyl alcohol, silicon rubber,cellulose propionate, melamine-formaldehyde resins, urea-formaldehyderesins, allyl casting resins, polymethyl methacrylate, polyesters,polyacrylonitrile, and copolymers of these polymers. Thecompounds mayalso be used for the stabilization of natural products such as rubber,cellulose, wool and silk.

The materials for stabilization may suitably be in the form of film orsheet, rods, coatings, panels, tapes, fibres, granules, powders or otherprocessing forms, or as solutions, emulsions or dispersions. Thestabilizing compounds may be incorporated in or coated on the materialsby conventional methods. An important method of application consists inintimately mixing polymeric material, for example polypropylenegranules, with the stabilizer in a kneader or other suitable machine,followed by extrusion. This method ensures homogeneous distributionwhich is important for good protection. The material can be extruded,for example, as film, tubing or filament, the latter for conversion intotextiles. In this method of application, the stabilizer may beincorporated in, for example, the polypropylene prior to textileproduction. The new stabilizers, however, can also be applied to textileyarns and fabrics from an aqueous medium containing a finely dispersedcompound of formula (1). This method is particularly suitable for, e.g.textiles of polyethylene terephthalate and cellulose acetate fibres.

Synthetic polymeric materials need not necessarily be in the final formbefore incorporation of the compounds of the invention. Thus, thesecompounds may be mixed with the monomers or prepolymers prior to thecondensation or other polymerization reaction giving the final polymer.

The new stabilizers are suitable for application to, for example, clearfilms and plastics, and are also suitable for stabilizing opaque,semi-opaque and translucent materials having a surface susceptible todegradation by ultra-violet radiation, air or heat. Examples of suchmaterials are foam plastics, opaque films and coatings, opaque papers,opaque and transparent pigmented plastics, fluorescent pigments,automobile and furniture polishes, creams, lotions and related products,which may be opaque, clear or translucent.

As regards the constitution of compounds of formula I and their action,it may be mentioned that particularly good stabilization is obtained inpolyalkylenes, notably polypropylene, when the molecule of the compoundof the invention consists to a large extent of saturated aliphaticgroups. When phosphonous acids of formula I in which R R R and Rrepresent hydrogen are employed in the form of the nickel salts, thestabilizing action against visible light and ultra-violet radiation isparticularly effective, especially in polyalkylenes. The manganese andcopper salts are particularly suitable for stabilizing polyamidesagainst degradation by ultraviolet radiation, while the salts of othertransition metals such as vanadium and cobalt, are suitable asultraviolet absorbers in a number of substrates.

The present invention also comprises the sensitive organic materialscontaining a compound of formula 1 for stabilization. As previouslyindicated, the new compounds can be incorporated in the organicmaterials at any stage of processing using standard methods. The amountsof stabilizer employed may vary within wide limits, for example from0.01 to 5% or preferably from 0.05 to 1% in relation to the weight ofthe material. The stabilized organic materials may contain compounds offormula I alone, or together with further additives, for exampleultra-violet absorbers and other stabilizers against degradation by heatand oxygen. As regards the latter, suitable stabilizers are thosebelonging to different chemical classes to the compounds of formula I,for example organic compounds of sulphur, tin and pentavalentphosphorus, sterically hindered phenols, 2- hydroxy-benzophenones andhydroxybenzotriazoles. Often, notably high stabilization may be obtainedwith such mixtures since they may have a synergistic action.

In the following Examples the parts and percentage are by weight and thetemperatures in degrees centigrade.

EXAMPLE A Production of an Intermediate of Formula I] c1 P IIc c1 isobtained in the form of a pale red oil with a pungent odour.

EXAMPLE 1 In the absence of moisture, a solution of 20 parts of thediphenylether dichlorophosphine of formula Ila, above, in 50 parts oftoluene is added at 0-5 to 29.9 parts of dodecyl mercaptan and 15 partsof triethylamine in parts of toluene. The solution is allowed to reactovernight at 40. Subsequently, the precipitated salt is filtered, thefiltrate evaporated under vacuum, and the residue crystallized fromabsolute ether. mp. 25 -26 Elementary analysis mi SH H found 9.9calculated 9.8

EXAMPLE 2 At 5, a solution of 33.4 parts of the diphenyletherdichloro-phosphine of formula l la, above, in 50 parts of toluene isadded to 50.7 parts of 2,4-ditert.butylphenol and parts of triethylaminein 200 parts of toluene in the absence of moisture. The solution isallowed to react overnight at the precipitated product filtered, thefiltrate evaporated under vacuum, and the residue crystallized fromether/methanol. m.p. 8889..

Elementary analysis P w sr a found calculated EXAMPLE 3 A solution of95.5 parts of 4,4-diphenylether-(bisdichloro-phosphine offormula 11c,above, in 50 parts of toluene is added, at 05, in the absence ofmoisture, to 21 1 parts of 2,4-di-tert.butylphenol and 104 parts oftriethylamine in 300 parts of toluene. The solution is allowed to reactovernight at 40, the precipitated product filtered, the filtrateevaporated under vacuum,

EXAMPLE 4 EXAMPLE 5 A solution of parts of4,4-diphenylether-(bischlorophosphine) in parts of toluene is added, at

15 0.-5, to 136.3 parts of 2,4-di-tert.butyl-4-phenyl phenol and 49parts of triethylamine in 300 parts of toluene, in the absence ofmoisture. The solution is allowed to react overnight at 40, theprecipitated salt filtered, the filtrate evaporated under vacuum, andthe residue triturated to a white powder. m.p. 8285.

EXAMPLE 6 A solution of 12.5 parts of4,4-diphenylether-(bisdichlorophosphine) in 50 parts of toluene is addedat and the residue triturated with methanol and crystal- 5 99 parts ofbutane] and 14 parts of triethylam lized from benzene. m.p. 7780.

ine in parts of toluene in the absence of moisture. The solution isallowed to react overnight at 40, the precipitated salt filtered and thefiltrate evaporated Element! analysis C H P under vacuum to yield a paleyellow oil. (Mil-205p: f 84 30 The structural formulae of the compoundsproduced calculated 77.6 8.8 5.9

m Examples 1 to 6 are shown in Table 1 below.

Table 1 Example 0 O P) NO. Q n

Significance of Q n l C H S- O 2 (tert.)H C 0 (tert. H C

3 do. l

(tert. H9C4 5 (teIt.)l'I9C4 O l (tert. H 6

USE EXAMPLE Polypropylene, which contains, as antioxidant, 0.2%

of 4,4'-Methylen-bis-(2,6-di-tert.butylphenol) is intimately mixed with0.1% of a compound produced in any one of Examples 1 to 6. The plasticis stored, in the form of thin discs, under oxygen in a closed systemafter removal of air. The system is then warmed to 190, whereby anexcess pressure of about mm Hg arises. The oxidation of the plastic isfollowed by fall in pressure. The speed of the fall in pressure is lowif the activity or the stabiliser or stabiliser mixture is high.Significantly improved results are obtained with poly propylene whichcontains in addition to 4,4- methylene-bis-(2,6-di-tert.butylphenol), acompound according to any one of Examples 1 to 6.

What is claimed is:

1. A compound of the formula P P QV R2 Y2 Y4 -r inwhich X signifies CHO, or -S,

Y Y Y and Y,, which may be the same or different, each signifies -O or-S,

R R R and R which may be the same or different, each signifies ahydrocarbon radical of up to 20 carbon atoms selected from the groupconsisting of alkyl; cycloalkyl which may be substituted by up to 3alkyl groups; cycloalkylalkyl; phenyl which may be substituted by up to3 alkyl or alkylcycloalkyl groups; diphenyl which may be substituted byup to 3 alkyl or alkylcycloalkyl groups; and phenyl 3. A compound ofclaim 1, in which Y Y Y and Y, are the same.

4. A compound of claim 1, in which R,, R R and R are the same.

5. A compound of claim 1, in which the substituent or each substituentis in the para position of the nucleus.

6. A compound of claim 1, in which rings A and B are I each furtherunsubstituted.

7. A compound of claim 1, in which R,, R R and R each signifies an alkylradical of l to 12 carbon atoms, a cycloalkyl radical of 3 to 12 carbonatoms, which may be substituted by l, 2 or 3 alkyl groups of l to 4carbon atoms, a cycloalkylalkyl radical in which the cycloalkyl portioncontains 5 to 12 carbon atoms and the alkyl portion l to 6 carbon atoms,or a phenyl or diphenyl radical which may be substituted by l, 2 or 3alkyl radicals of l to 12 carbon atoms.

8. A compound of claim 1, in which R R R and R, each signifies an alkylradical of l to 6 carbon atoms, a cycloalkyl radical of 5 to 8 carbonatoms, which may be substituted by l, 2 or 3 alkyl groups of l to 4carbon atoms, a cycloalkylalkyl radical in which the cycloalkyl portioncontains 5 to 8 carbon atoms and the alkyl portion contains 1 to 4carbon atoms, or a phenyl or diphenyl radical which may be substitutedby 1, 2 or 3 alkyl radicals of l to 6 carbon atoms.

9. A compound of claim 1, in which R,, R R and R, each signifies analkyl radical of 4 to 12 carbon atoms, or phenyl or diphenyl radical,which may be substituted by l or 2 alkyl radicals of l to 4 carbonatoms.

10; A compound of claim 1, in which R,, R R and R, each signifies otherthen a tertiary alkyl radical.

11. A compound of claim 1, in which R R R and R each signifies n-butyl,n-dodecyl, 2,4-di-tbutylphenyl, 2-t-butylphenyl, or2,4-di-t-butyldiphenyl.

12. A compound of claim 2 in which Y Y Y and Y, are the same.

13. A compound of claim 2 wherein R R R and and diphenylalkyl, the arylportions of which may R4 are h same be substituted by up to 3 alkylgroups. 14. A compound of claim 3 wherein R R R and and rings A and Bmaybe either unsubstituted or R4 are the Same each further substitutedby 1 or 2 alkyl groups of 15 A compound f l i 12 i hi h R 12,, R and lto 6 carbon atoms. R are the same. 2. A compound of claim 1, in which Xsignifies 16' The compound of claim 1 of f ul --O.

t-C l l t-C H u l u u 9 3; c n o\ 1/0 3;, (2 x1 /P- -op\ a j; C H =[-O OH 1; C 3

17. The compound of claim 1 of formula PQO-QQQ 18. The compound of claim1 of formula gc H 19. The compound of claim 1 of formula

1. A COMPOUND OF THE FORMULA
 2. A compound of claim 1, in which Xsignifies -O-.
 3. A compound of claim 1, in which Y1, Y2, Y3 and Y4 arethe same.
 4. A compound of claim 1, in which R1, R2, R3 and R4 are thesame.
 5. A compound of claim 1, in which the
 6. A compound of claim 1,in which rings A and B are each further unsubstituted.
 7. A compound ofclaim 1, in which R1, R2, R3 and R4 each signifies an alkyl radical of 1to 12 carbon atoms, a cycloalkyl radical of 3 to 12 carbon atoms, whichmay be substituted by 1, 2 or 3 alkyl groups of 1 to 4 carbon atoms, acycloalkylalkyl radical in which the cycloalkyl portion contains 5 to 12carbon atoms and the alkyl portion 1 to 6 carbon atoms, or a phenyl ordiphenyl radical which may be substituted by 1, 2 or 3 alkyl radicals of1 to 12 carbon atoms.
 8. A compound of claim 1, in which R1, R2, R3 andR4 each signifies an alkyl radical of 1 to 6 carbon atoms, a cycloalkylradical of 5 to 8 carbon atoms, which may be substituted by 1, 2 or 3alkyl groups of 1 to 4 carbon atoms, a cycloalkylalkyl radical in whichthe cycloalkyl portion contains 5 to 8 carbon atoms and the alkylportion contains 1 to 4 carbon atoms, or a phenyl or diphenyl radicalwhich may be substituted by 1, 2 or 3 alkyl radicals of 1 to 6 carbonatoms.
 9. A compound of claim 1, in which R1, R2, R3 and R4 eachsignifies an alkyl radical of 4 to 12 carbon atoms, or phenyl ordiphenyl radical, which may be substituted by 1 or 2 alkyl radicals of 1to 4 carbon atoms.
 10. A compound of claim 1, in which R1, R2, R3 and R4each signifies other then a tertiary alkyl radical.
 11. A compound ofclaim 1, in which R1, R2, R3 and R4 each signiFies n-butyl, n-dodecyl,2,4-di-t-butylphenyl, 2-t-butylphenyl, or 2,4-di-t-butyldiphenyl.
 12. Acompound of claim 2 in which Y1, Y2, Y3, and Y4 are the same.
 13. Acompound of claim 2 wherein R1, R2, R3, and R4 are the same.
 14. Acompound of claim 3 wherein R1, R2, R3, and R4 are the same.
 15. Acompound of claim 12 in which R1, R2, R3, and R4 are the same.
 16. Thecompound of claim 1 of formula
 17. The compound of claim 1 of formula18. The compound of claim 1 of formula
 19. The compound of claim 1 offormula